The present invention relates to a method of recycling a medium carrying an image printed in thermo-softening ink by removing the image from the medium, and an image separating member therefor. More particularly, the present invention is concerned with a method of recycling a copy sheet by separating a toner image therefrom, and an image separating member therefor.
Today, a tremendous number of sheets are used in offices for printing and copying purposes and has invited the disruption of global environment due to lumbering. It has been customary to recycle or regenerate used sheets by removing ink from them, melting them down, and then making fresh sheets. A recent achievement in the resource saving art is a method capable of removing character images from used sheets by cleaning so as to recycle them for printing and copying purposes. This kind of method is disclosed in the following documents (1)-(3) by way of example.
(1) Japanese Patent Laid-Open Publication Nos. 4-64472 & 4-67043 PA0 (2) Japanese Patent Laid-Open Publication Nos. 1-101576 & 1-101577 PA0 (3) Japanese Patent Laid-Open Publication No. 1-297294
Methods taught in these documents apply a silicone seal agent or similar parting agent to the surface of a fresh sheet and then dry it to produce a reusable or erasable sheet. An image is formed on the surface of the sheet carrying the parting agent thereon. To recycle the sheet, thermo-fusible resin, or toner resin for forming an image, is adhered to the sheet in order to remove the image. Such a method, however, brings about the following problems (i)-(v).
(i) An image is formed on the parting agent and cannot, of course, be stably fixed on the sheet.
(ii) Since the image is mechanically stripped off from the sheet by the toner resin while the sheet is heated, the toner resin penetrated into the fibers of the sheet cannot be fully removed. Hence, the recycling efficiency is extremely low.
(iii) Duplex copying, i.e., reproducing an image on both sides of a single sheet is important from the resource recycling standpoint and will become predominant in the future. In this respect, applying the parting agent to only one side of a sheet is not efficient.
(iv) Even if the parting agent is applied to both sides of a sheet and then dried, the silicone seal agent will penetrate into the sheet and render the resulting sheet semitransparent. Images reproduced on both side of such a sheet will be illegible.
(v) The erasable sheets should be distinguished from plane sheets in the event of copying, further lowering efficiency. It is difficult to stack the erasable papers together with plane papers and reproduce images thereon.
A medium carrying an image thereon is immersed in an organic solvent which dissolves toner resin constituting the image. Then, the medium is treated by supersonic waves to remove the image. The problem with this method is that a great amount of organic solvent is required in order to dissolve and remove the toner resin. This not only increases the overall size of a processing apparatus but also gives rise to other various problems including the regeneration of the solvent, inflammability, toxicity and environmental pollution. Therefore, this kind of procedure is not feasible for offices and homes.
The image carrying medium is implemented as a sheet of plastic, metal, paper with low liquid infiltration or ceramic. An image formed on the medium is heated with the intermediary of a thermo-fusible image separating member. As a result, the image is stripped off from the medium. This cleaning method, however, needs a special sheet, or erasable paper, whose surface is treated for parting and is not applicable to ordinary sheets used in a great amount for copying and printing.